Vacationing in New Zealand

We are planning to take a vacation to New Zealand, and we are looking for some recommendations for places we should be sure to visit. We are definitely planning to visit Ruapehu, so we are reserving Ruapehu accommodation for at least a few days of our trip if not the whole thing. It would be nice if we could just make that our base of operations and travel to other places on day trips, but I am not sure whether or not this is going to be possible. It depends on where we decide to visit and the distances involved.